1. Technical Field
The present invention relates to a method of manufacturing a phosphor for a light-emitting diode and, more particularly, to a method of manufacturing a phosphor which converts light provided by the light-emitting diode into white light by changing a wavelength of light emitted from the light-emitting diode.
2. Description of the Related Art
Recently, a light-emitting diode in which Al or In is added to GaN has been in the spotlight owing to a long lifespan, low power consumption, excellent brightness, and an eco-friendly element not harmful to the human body as compared with a conventional incandescent. In particular, a light-emitting diode providing white light has been further in the spotlight.
The light-emitting diode is being used in a vehicle illumination, a traffic signal lamp, and the Back Light Unit (BLU) of a liquid crystal display owing to the above-described advantages.
MacAdam's ellipse rule has recently been proposed as an index for evaluating whether a color coordinate measured at an artificial light source is identical with a color coordinate when being seen by an eye of a human being. MacAdam's ellipse rule provides a four-step criterion. In the United States, currently, an artificial light source that does not comply with three steps of MacAdam's ellipse rule is not allowed to be sold. In order to satisfy the three steps of MacAdam's ellipse rule, it is very important to reduce a color variance in white light.
Meanwhile, Korean Patent Laid-Open Publication No. 10-2008-0070193 discloses a phosphor light emitting diode and a method for manufacturing the same. However, the invention disclosed in the Korean Patent Laid-Open Publication is problematic in that a phosphor film is deteriorated because the phosphor film is attached by a thermal printing process. It has been known that this problem has a great defect in reliability that is most important in a white light light-emitting diode. Furthermore, there is a problem in that manufacturing expenses are increased when a fluorescent film is attached by a thermal printing process.